soft starter starting current calculation

We presume, you've carried out the motor starting study with your other base load ON and established the Voltage drop at the bus.

current. 3.1 "Soft-start" or Voltage Regulators Voltage regulators, DC/DC converters, and LDOs may have an integrated soft-start functionality. With this feature, the rise time can be increased, thereby reducing the inrush current. With a properly selected DC/DC converter or LDO, the inrush can be effectively managed to ensure system stability.

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Step 1 - Calculate the required starting kVA from: ‐ Start factor x motor rated kVA. (Where start factor = (per unit soft starter pedestal voltage) 2 x LRC factor and LRC factor = Locked Rotor Current (Amps)/Full Load Current (Amps)). [Can be found in the motor manufacturer's data.]

6/21 · Abstract: This paper presents a sensorless starting procedure for a soft starter driven IE4 direct on line permanent magnet motor (PMSM). After determining the initial position of the motor using a pulsating current space vector, the motor is started from standstill by the soft starter from a known position.

In your case the nameplate gives the start-to-rated current ratio, Ia/In, as 7.5. This means that if rated voltage were applied to the motor, and its stator winding was delta-connected, then its starting current will be 7.5 x 160 or 1,200 Amperes. In certain instances, such a current is prohibitive.

Actually, the current during the first half cycle of the electrical supply can be >20x nominal FLC A typical picture of the current and voltage in a direct-on-line motor-pump system is shown below. The current is shown in green, and the voltage in purple.

12/3 · Sometimes named pedestrian voltage or torque, this is the point from where the softstarter starts or stops its ramps. The torque of the motor will drop with the square of the voltage and if the voltage is set too low, for example 20 %, the starting torque will become 0.22 = 0.04 = 4 % only, and the motor will not start from the very beginning.

In order to mitigate the adverse effects of starting torque transients and high inrush currents in induction motors, a popular method is to use 

Sometimes named pedestrian voltage or torque, this is the point from where the softstarter starts or stops its ramps. The torque of the motor will drop with the square of the voltage and if the voltage is set too low, for example 20 %, the starting torque will become 0.22 = 0.04 = 4 % only, and the motor will not start from the very beginning.

Electronic soft starter can make the motor with voltage ramp start from initial voltage to full voltage at the set time (0.5 to 2408). Like it can reduce water impact if we extend the time of water pump flow from 0 to 100%, increase the pump speed variation time means increase the starting time which can be achieved by adjusting the starting